hmm thats screwed - this is what Lead Pursuit used to recommend:
If anyone is having issues uninstalling Allied Force, please try the following:
Go to this page http://support.microsoft.com/default.aspx?...kb;en-us;290301
Halfway down is the download link to grab the Installer Cleanup Utility package.
Once you have downloaded the file, double click it and select "Run". This will install the package.
Go to C:\Program Files\Windows Installer Clean Up and double click "msicuu.exe"
In the list of programs that appear in the new window, choose (All Users) Falcon 4.0: Allied Force .... and at the bottom hit "remove".
This should allow you to reinstall AF correctly.